I need to prove:
lim (x^4)-(2(x^2)) = +inf
x->+inf
Any suggestions?
You want to show that for every , there exists such that whenever , it necessarily follows that
Consider the latter expression as an equality:
(since and )
(we're considering positive x's)
So when we have that . We want to show that for some , we have that
Now consider: . Can you finish?